1. Field of the Invention
The present invention relates to measuring devices and methods for using the same, and particularly to, a measuring device and a method for using the same with a high precision.
2. Discussion of the Related Art
Typically, machine tools are preferred over hand tools because machine tools exhibits high machining precision, can easily be changed into computerized automated systems, and other advantages. Therefore, machine tools are widely used in the manufacturing field. Referring to FIG. 5, a conventional machine tool 10 includes a main body 110, a slidable platform 12, and a controller (not shown). A pair of horizontal guide rails 111 are fixed on the main body 110 and the slidable platform 12 is slidably disposed on the horizontal guide rails 111. Generally, because of manufacturing precision and wear and tear, a gap may be defined between the slidable platform 12 and the horizontal guide rails 111. When the slidable platform 12 slides on the horizontal guide rails 111, the slidable platform 12 may wobble due to the gap, thus the precision of the machining tool 10 decreases. In order to increase the precision of a measuring device, information on the wobble deviation should be taken into account. This wobble deviation information can be used to modify some machining parameters to improve the machining precision of the machine tool 10.
Referring to FIG. 6, a measuring device 20 includes a laser device 201, a collimator 202, a diffraction grating 203, four reflectors 204, two combiners 205, two magnifiers 206, two photoelectric detectors 207, and a processor (not shown). The diffraction grating 203 is fixed on a bottom surface of the slidable platform. The laser device 201 is fixed on the main body opposite to the diffraction grating 203. A laser beam emitted from the laser device 201 enters the diffraction grating 203 and is splitted into four laser beams Y1, Y2, Z1 and Z2. The four laser beams Y1, Y2, Z1 and Z2 are reflected by the corresponding reflectors 204. The laser beams Y1 and Y2 combine with each other to form a laser beam L1, while the laser beams Z1 and Z2 combine with each other to form a laser beam L2. The two laser beams L1 and L2 are magnified by the corresponding magnifiers 206, and enter the corresponding photoelectric detectors 207 in succession. The photoelectric detector 207 transforms an optical signal from the laser beam L1 or L2 to an electric signal, and sends the electric signal to the processor. When the slidable platform wobbles relative to the horizontal guide rails, an intensity and a direction of the laser beams Y1, Y2, Z1 and Z2 are changed. Therefore, an intensity and a direction of the laser beams L1 and L2 are also changed. The deviation from the predetermined path of the slidable platform can be measuring via analyzing the intensity and the direction of the laser beams L1, L2.
However, the diffraction grating 203 is fixed on the bottom surface of the slidable platform, thus the diffraction grating 203 is easy to become loosen from the slidable platform due to the movement of the slidable platform. Further, the diffraction grating 203 is a precision optical element, a tiny change of the position of the diffraction grating 203 should lead to a great measuring error of the measuring device 20.
Therefore, a measuring device and a method for using the same which can overcome the above-described problem are desired.